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java - 如何使用 multipart/form-data 在服务器中上传文件?

转载 作者:行者123 更新时间:2023-12-02 04:59:51 25 4
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我在 jsp 中编写了一个程序,用于上传在 webcontent 中创建的名为 images 的文件夹中的文件,但我的文件没有上传。请需要一些帮助。

<form action="upload_images_result.jsp" method="post">
<div align="left">
Select a file: <input type="file" name="file" size="50"
enctype="multipart/form-data" placeholder="Upload Your Image" />
</div>
<br>
<div>
<input type="submit" value="Upload File" />
</div>
</form>

upload_images_result.jsp

<%
File file;
int maxFileSize = 5000 * 1024;
int maxMemSize = 5000 * 1024;
//ServletContext context = pageContext.getServletContext();
String filePath = "D:\\Students_Server\\WebContent\\Images";
// Verify the content type
String contentType = request.getContentType();
if ((contentType.indexOf("multipart/form-data") >= 0)) {

DiskFileItemFactory factory = new DiskFileItemFactory();
// maximum size that will be stored in memory
factory.setSizeThreshold(maxMemSize);
// Location to save data that is larger than maxMemSize.
factory.setRepository(new File(
filePath "));
// Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload(factory);
// maximum file size to be uploaded.
upload.setSizeMax(maxFileSize);
try {
// Parse the request to get file items.
List fileItems = upload.parseRequest(request);
// Process the uploaded file items
Iterator i = fileItems.iterator();

out.println("<html>");
out.println("<head>");
out.println("<title>JSP File upload</title>");
out.println("</head>");
out.println("<body>");
while (i.hasNext()) {
FileItem fi = (FileItem) i.next();
if (!fi.isFormField()) {
// Get the uploaded file parameters
String fieldName = fi.getFieldName();
String fileName = fi.getName();
boolean isInMemory = fi.isInMemory();
long sizeInBytes = fi.getSize();
// Write the file
if (fileName.lastIndexOf("\\") >= 0) {
file = new File(filePath +
fileName.substring(fileName.lastIndexOf("\\")));
} else {
file = new File(filePath +
fileName.substring(fileName.lastIndexOf("\\") + 1));
}
fi.write(file);
out.println("Uploaded Filename: " + filePath + fileName + "
<br>");
}
}
out.println("</body>");
out.println("</html>");
} catch (Exception ex) {
System.out.println(ex);
}
} else {
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet upload</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>No file uploaded</p>");
out.println("</body>");
out.println("</html>");
}
%>

输出打印为“未上传文件”

谢谢

最佳答案

当您发出 POST 请求时,您必须以某种方式对构成请求正文的数据进行编码。

HTML 表单提供了三种编码方法。

  • application/x-www-form-urlencoded(默认)
  • 多部分/表单数据
  • 文本/纯文本

使用enctype=multipart/form-data当您的表格包含任何<input type="file">时元素。

所以使用

<form action="upload_images_result.jsp" method="post" enctype="multipart/form-data">
<div align="left">
Select a file: <input type="file" name="file" size="50"
enctype="multipart/form-data" placeholder="Upload Your Image" />
</div>
<br>
<div>
<input type="submit" value="Upload File" />
</div>
</form>

关于java - 如何使用 multipart/form-data 在服务器中上传文件?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28393449/

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